How to use
- Enter the distance in miles or kilometres, or pick a race distance.
- Enter your time as h:mm:ss or mm:ss.
- Read your pace, speed and predicted times for other distances.
Options explained
- Pace
- Time per mile or kilometre; lower is faster.
- Race predictions
- Riegel's formula: T2 = T1 × (D2 ÷ D1)^1.06. Best for trained runners and similar distances; predicting a marathon from a 5K is often optimistic.
Examples
| Distance | Time | Pace | 10K | Half | Marathon |
|---|---|---|---|---|---|
| 5 km | 25:00 | 5:00 /km | 52:07 | 1:55:00 | 3:59:47 |
| 5 km | 27:30 | 5:30 /km | 57:20 | 2:06:30 | 4:23:45 |
| 10 km | 50:00 | 5:00 /km | — | 1:50:19 | 3:50:01 |
Frequently asked questions
What pace do I need for a four-hour marathon?
About 9:09 per mile (5:41 per km). A three-hour marathon needs about 6:52 per mile (4:16 per km).
How accurate are the predictions?
They are close for trained runners over similar distances. Without long training runs, a marathon is usually slower than predicted from a 5K.
Can I switch between miles and kilometres?
Yes. The distance converts when you switch units, and the pace is shown per the chosen unit.
Privacy
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